1. Field of the Invention
The subject invention relates to the disc brakes and, more specifically, to a method of fabricating the braking surfaces on the brake disc.
2. Description of the Prior Art
With the advent of front wheel drive vehicles and disc brakes, the assembly which is driven by the drive shaft comprises a hub presenting a disc flange supporting a rotor having opposed braking surfaces and with a bearing assembly surrounding the hub with an outer race presenting a support flange for attachment to a king pin of a vehicle. When fully assembled on the vehicle, the braking surfaces of the disc rotor are disposed adjacent the brake pads of the brake disc assembly and separated from engaging the braking surfaces by a brake running clearance when the brake piston is not actuated. When the brake piston is actuated, the brake pads take up the clearance and engage the braking surfaces.
In order to provide this uniform running clearance, and to avoid adverse wear of the disc when the brakes are not applied, the disc rotor must be manufactured to close tolerances with the braking surfaces oriented radially or perpendicularly to the axis of rotation of the rotor when installed. A method of machining to close tolerances on a disc which is mounted through a bearing on a fixed stub shaft is disclosed in U.S. Pat. No. 5,430,926 issued Jul. 11, 1995 to D. J. Hartford. Normally, however, in a front drive or driven wheel, a bearing assembly is disposed about the hub, rather than in the hub as in the aforementioned patent, and after the braking surfaces have been machined. As the bearing assembly is mounted to the vehicle, the bearing assembly is loaded to finalize the relationship or orientation between the braking surfaces and the axis of rotation and can result in misalignment of the braking surfaces. A method of machining a brake disc assembly which moves the art forward is disclosed and claimed in co-pending application Ser. No. 08/807,079 filed Feb. 27, 1997 in the names of Raymond C. Rapisardi and Vince J. Austin, and in co-pending application Ser. No. 08/859,696 filed May, 21, 1997 in the names of Glenn Kochan and Vince J. Austin. However, perfections are yet to be made in this new method.